just got approved and it sure is pretty. The system received an overall speed boost to better handle future HD content and "deep color." This will be used to support 1080 X 60 Hz with 36-bit RGB color, or 1080p with 90Hz. The big news comes with the bump up of RGB
support. The current HDMI spec "only" supports up to 24-bit RGB which is truly all the eye can see. 1.3 however allows for 30, 36, and even 46-bit color. Most of the time when 36-bit color is utilized, it is for GUI overlays and things of that nature. This allows for the image underneath not to be modified when the overlay is present. Even so, this will allow for over 1 billion possible colors. The PS3 is said to take advantage of this and could have even been one of the reasons it was delayed.
HDMI 1.3 will also support the lossless formats of Dolby HD and DTS-HD along with a new type of HDMI connector for smaller HD devices. It seems that this new mini connector is what Sony has put on their newest SXRD-based XBRs
but left off of the A2000 line. Lastly, 1.3 has a system built-in similar to Panasonic Viera Link.
It allows for the HDMI device to configure the HDMI display - in since they will talk to each other.
[via Extreme Tech